Proposal Information for 2001A-0355

CoI: David Koerner, University of PennsylvaniaCoI: Beth Biller, Harvard-Smithsonian Center for AstrophysicsCoI: Allyn Dullighan, Swarthmore College

Title: Searching for the nearest young stars

Abstract: Recent observations have revealed the presence of a handful of ~ 10-Myr-old stars (of which TW Hya and HD 98800 are the best known) at a distance of only ~ 50 pc. These observations suggest that there may be previously unrecognized pre-main-sequence stars near the Sun, either in a distributed population or in small clusters that are no longer associated with molecular gas. In order to search for additional stars in this population, we have selected nearby candidate young stars based on chromospheric activity (from the ROSAT Bright Source Catalog) and HR-diagram position (from the Hipparcos Catalog). We propose here to conduct follow-up spectroscopic observations to search for strong lithium absorption (an indicator of youth) from these stars. Unlike most previous searches for isolated young stars, this selection method is not biased in favor of stars with disks. Thus, young stars found in this survey will serve as a useful sample for SIRTF observations to provide constraints on protoplanetary disk evolution in the crucial planet-building phase at ages of 10-100 Myr; the relative nearness of these stars will allow SIRTF detection of tenuous disks that are below the IRAS sensitivity limit and may allow imaging of disks or substellar companions. Whether or not additional young stars are found, this survey will provide constraints on recent star formation in the solar neighborhood.